特种风洞试验中气动伺服弹性失稳故障分析

在某带飞行控制系统的特种风洞试验中,试验模型在闭环大增益情况下出现了振动发散现象。为分析故障原因,对试验数据进行了频谱分析并检验了无风情况下伺服稳定性;同时,将风洞试验动力学系统简化为数学模型,并建立相应的运动微分方程进行分析,得到以下结论:加入支持结构后整个系统的弹性影响较大,并与控制及气动力发生耦合出现气动伺服弹性失稳。进一步针对以上简化模型,进行数值仿真,其结果验证了以上机理。为解决此失稳问题,对控制系统提出了2种改进方案:增加结构陷波器或更改操纵面偏转比例参数,2种方案亦得到仿真验证。最后,将增加结构陷波器的改进方案应用到试验中,达到了预期的效果。 

Aeroservoelastic unstability failure analysis in special wind tunnel test

In an already completed wind tunnel test where a flight control system was applied, the vibration divergence of the test model under big closed-loop gain has drawn our attention. To find the mechanism of this failure, the frequency analysis of the test data has been done and the servo stabilization under no wind condition has been examined. Also, we built a simplified structural mechanic model according to the real situation and investigated the problem by analyzing the related differential equation of motion. The main cause for this failure has been found:the unexpected elastic effect after the involving of support system is significant and thus the coupling of elastic structure, control system and aerodynamic force gives rise to the aeroservoelastic instability. In addition, a numerical simulation has been done and verified the above mechanism. To solve this divergence problem, two improvements/solutions for the control system have been brought up:adding a structure filter in the feedback loop or changing the gain parameters of different control surfaces. Also, both the solutions have been verified by numerical simulation. The solution of adding a structure filter has been applied in the real wind tunnel test and expected effect has been achieved.